Insertion element for inserting weft threads on a loom

ABSTRACT

A shuttle for inserting a weft thread into a shed of a loom, the shuttle comprising a body of conchoidal shape, having two sidewalls that are connected along a closed edge portion of the body and are open over the remaining portion of the body; retaining means in the interior of said body for retaining a portion of thread of predetermined length in the form of a coil between said walls; and the interior of the body being so shaped that during its operation on the loom the interior is automatically cleaned of particles of fibers and like contaminants; said body defining a path for the removal of said particles and there being no obstruction along this path that inhibits the discharge of said particles therefrom. The portion of thread to be inserted is wound on a coil-forming member and then transferred to the shuttle by pushing the shuttle over the coil located on the coil-forming member in a direction at right angles to the axis of said member and by moving the shuttle away from the coil-forming member in a direction parallel with the axis of said member.

mted States Patent 1151 3,640,313 Strauss 1 Feb. 8, 1972 [54] INSERTION ELEMENT FOR INSERTING FOREIGN PATENTS OR APPLICATIONS WEFT THREADS ON A LOOM 452,453 5/1968 Switzerland 139/12 [72] Inventor: Edgar H. Strauss, Ruti/Zurich, Switzerland Primary ExaminerHenry S. Jaudon Attorney-Donald D. Denton [73] Assignee: Ruti Machinery Works, Ltd., formerly Casper Honegger, Ruti/Zurich, Switzer- [57] ABSTRACT land 22 i J 26, 1970 A shuttle for inserting a weft thread into a shed of a loom, the [21 J A I 5 837 shuttle comprising a body of conchoidal shape, having two pp sidewalls that are connected along a closed edge portion of the body and are open over the remaining portion of the body; [30] Foreign Application Priority Data retaining means in the interior of said body for retaining a portion of thread of predetermined length in the form of a coil Feb. 19, Sw1tzerland between Said walls; and the interior of the y being so shaped that during its operation on the loom the interior is au- [52] U S C] 1 39/12 tomaticauy cleaned of particles of fibers and like contami nants; said body defining a path for the removal of said partil cles and there being no obstruction along this path that inhibits the discharge of said particles therefrom. The portion of [56] Refer nc s Ci thread to be inserted is wound on a coil-forming member and then transferred to the shuttle by pushing the shuttle over the UNITED STATES PATENTS coil located on the coil-forming member in a direction at right 3,311,136 3/1967 Rossman ..139 12 angles the axis Said member and by "Wing the Shuttle away from the coil-forming member in a direction parallel with the axis of said member.

14 Claims, 5 Drawing Figures PATENTED FEB BIBTZ 3.640.313

sum 1 or 2 PATENTED FEB 8 I972 SHEET 2 UF 2 Fig. 3

INSERTION ELEMENT FOR INSERTING WEFT THREADS ON A LOOM This invention relates to a shuttle or insertion element for the insertion of weft threads into a shed-of a loom and more particularly to a shuttle adapted to be used with a thread coilforming member, the shuttle being of conchoidal shape, having retaining means in its interior for retaining a portion of thread in the form of a coil of predetermined length therein and being designed to be automatically cleaned of contamination, e.g., lint, fibers, dirt, etc., during its use on a loom. The portion of thread to be inserted into the shed is wound as a coil on the coil-forming member and is transferred to the shuttle by pushing the shuttle over the coil (located on the coil-forming member) in a direction at right angles to the longitudinal axis of the member and by moving the shuttle away from the coil-forming member in a direction parallel with the axis of the member.

In wave-type looms or multiphase weaving machines presently known, a plurality of shuttles or insertion elements insert weft threads into each of the changing sheds formed during the weaving operation. Before the shuttles successively run into the sheds the threads are placed in predetermined lengths as coils or windings in the interior of the shuttles and are continuously withdrawn from them again during their passage through the sheds. While this is happening, it is impossible to prevent the occurrence of a certain amount of contamination of the shuttles, particularly loose fibers adhering thereto. If these fibers combine to form small fibrous clusters, it may happen that the fibrous clusters are carried along on the weft threads when the threads are being withdrawn from the shuttles, and the clusters are then woven into the fabric. Consequently, the quality of the fabric obtained suffers.

In the case of shuttles of the type similar to those of this invention it is known to provide two fibrous inserts, e.g., plush inserts, or linings, in their interior. The purpose of these in serts is to retain the coils of thread when they are pulled off the coil-forming member. When such an insert is employed a relatively large number of fibers naturally adhere thereto, so that with such an arrangement the above-mentioned problem of contamination is of relatively great importance.

In accordance with this invention, the mode in which the shuttles operate, particularly in conjunction with the coilforming member, and also in conjunction with the action of withdrawing the threads from the shuttles during the weaving operation, is utilized for automatically cleaning the shuttles. This results in the advantage that separate cleaning devices are not necessary. Thus, this invention contemplates a shuttle which is further characterized in that it has an elongated body that is so shaped that, during operation, its interior is automatically cleaned of contamination, said body including means for providing a path or passage for the removal of particles or fibers of thread and the like contamination from the shuttle and there being no parts along this path which inhibit the discharge of the contamination.

The invention will now be described in more detail with reference to its specific embodiments and to the accompanying drawings, in which:

FIG. 1 is a side view of a shuttle of this invention and of a portion of a coil-forming member on a wave-type loom;

FIG. 2 is a sectional view of the shuttle taken along line II II of FIG. 1, on a greater scale;

FIG. 3 is a sectional view through the shuttle taken along line IllIlI of FIG. 1 on a greater scale;

FIG. 4 is a side view of a thread guide used in the shuttle of the invention; and

FIG. 5 is a cross-sectional view through another embodiment of the shuttle of this invention.

In all the figures the same reference numerals are used for indicating like elements.

The insertion element or shuttle 11 shown in FIG. I has an elongated body which is of conchoidal form, i.e., the body has a shape like a bivalve mollusk shell. The body has two sidewalls 12 and 13. These are interconnected along the edge or closed portion 14. The sidewalls 12 and 13 are separated from each other over the remaining open portion of the periphery of the body. Each of the sidewalls 12 and 13 contains an elongate orifice or slot 16 or 17, respectively. A retaining element or projection 18 is inserted in the slot 16, and a retaining element or projection 19 in the slot 17. These retaining projections 18 and 19 fit exactly into the slots 16 and 17.

Inside the shuttle 11 are two inserts which provide retaining means for holding or retaining a coil of thread within the shuttle. Each of these inserts includes a resilient or cushion material 20 or 21, respectively. This resilient material can, for example, be foam rubber. The material'20 is wrapped in a sheet material 22, and the material 21 in a sheet material 23. Sheet materials 22 and 23 are each flexible and have a surface that provides relatively good sliding properties and that is somewhat rough or uneven. One example of a material that may be used advantageously in this respect is a synthetic fabric, such as a nylon fabric.

A plate 24 or 25, respectively, is passed through each of the inserts. The plate 24 is located between the cushion material 20 and the sheet material 22 adjacent to sidewall 12, and the plate 25 is located between the cushion material 21 and the sheet material 23 adjacent to sidewall 13. The plates 24 and 25 are preferably made of metal. At each of their ends (see FIG. 3) the plates have two end portions 26, 27 and 28, 29 which are biased towards each other. The bias is provided by the resilient supporting arms 30, 31 and 32, 33. On the one hand, these arms press the plates 24 and 25 outwards and, on the other, ends 26, 27 and 28, 29 towards each other. The end portions 26 and 27 are designed to cooperate to provide a thread-brake for the thread emerging from the shuttle 11 as the shuttle passes through a shed formed during the weaving operation.

Rivets 15 are provided for securing the plates 24 and 25 to the retaining elements or projections 18 and 19. In the embodiments illustrated in FIGS. 2 and 5, the rivets 15 also penetrate the sheet material 22 and 23 so that this is also secured to each respective insert. The outward pressure on the plates 24 and 25 causes the retaining projections 18 and 19 to lie fiush in the slots 16 and 17. In this way the inserts 20, 22 and 21, 23 are accurately positioned within the body of the shuttle.

As can be seen from FIGS. 1 and 2, the shuttle 11 contains, below the edge 14, connecting the two shuttle walls 12 and 13, an unoccupied space 34 which (as shown in FIG. I) is open at the right end of the shuttle. In order to prevent the weft thread, which runs out of the thread-brake 26, 27 in the upward direction at an angle of approximately 45, from moving out of the thread-brake 26, 27 and passing into the unoccupied space 34, there is provided a thread guide or guide means 35. This guide means is shown in side view in FIG. 4. The guide means comprises a plate 36, which contains an orifice or slot 37, which fits precisely over the retaining projection 18. When the thread guide 35 is fitted in the body of shuttle 11, the plate 36 lies between the sheet material 22 and the wall 12 of the shuttle. The thread guide 35 comprises a resilient portion 38 which is positioned at an angle to the portion containing slot 37. This portion biases the extensions 39 and 40 in the direction of the wall 13 of the shuttle. The weft thread, running out of the shuttle 11 during the travel of the shuttle through a shed, is guided by the slot 41, which is formed in the extensions or projections 39 and 40. A notch 42 is provided so as to obtain a predetermined amount of movement of the projection 40 when the coils of thread are transferred to the shuttle l 1.

Reference will now be made to FIG. 1 for the purpose of describing how the coils of thread are passed to the shuttle 11. The coils of thread 43 are formed by a rotor, not illustrated, on a stationary coil-forming member 44.

As soon as a coil has a number of turns such that it con stitutes a portion of thread of the desired determined length, it is moved along the member 44 (i.e., to the left as seen in FIG.

1) onto a portion in which the thread is located below the point from which the shuttles 11, for inserting the weft threads, are pushed downwards in a continuous sequence. it is generally advantageous if the coil-forming member 44 takes the form of a blade, i.e., if it is very narrow or thin at right angles to the plane of the drawing. In order to enable the coils of thread 43 to slide along as easily as possible, the coil-forming member 44 is slightly tapered towards its free end, i.e., toward the left end.

ln order to pass the coil 43 to the shuttle l1, i.e., to pass the coil into the interior of the shuttle, the shuttle is pushed downwards at a right angle to the axis 45, over the upper edge of the member 44. As this happens the member 44 and the coil 43, located thereon, pass between the opposed sides of the inserts including elements 20, 22 and 21, 23, respectively. The end portions 26, 27 and 28, 29 are pressed slightly away from each other, overcoming the bias provided by the resilient supporting arms 30, 31 and 32, 33. At the same time the member 44 encounters the projection 39 and lifts it from the sidewall 13. The projection 40 is lifted at the same time. If the notch 42 is sufficiently deep, the projection 40 is lifted higher than the projection 39. lf this is the case, it is impossible for the nose of the projection 40 to foul the member 44. In order to meet this requirement, the notch must extend to approximately the level of that point on the projection 39 farthest to the right as shown in FIG. 4. For the sake of greater clarity, the position occupied by the member 44 in the shuttle ll pushed over it is indicated in FIG. 1 by the dash-and-dot line 44'.

If the shuttle I1 is now moved to the left, as seen in FIG. 1, and parallel with the axis 45, the coil of thread 43 is held by the two mutually facing surfaces of the inserts 20, 22 and 21, 23 and is thus drawn off the member 44. As this happens, the individual turns remain in the same position that they occupied on the member 44. The shuttle 11 is passed from the coilforming member through a shed. During this movement the weft thread is continuously withdrawn obliquely and upwardly at the rear end of the shuttle 11 through the thread-brake 26, 27 at an angle of approximately 45 from the horizontal.

As originally mentioned, fibers become deposited in the interior of the shuttle 11 and these lead to gradual contamination of the shuttle. in the case of known shuttles, in which are provided inserts which have bristles or plush-type lining extending towards the central plane or plane of symmetry of the shuttle, this depositing of fibers is still more pronounced. Some of these known shuttles also have a thickened portion in the edge portion 14 at their upper rear ends, by means of which the weft thread, emerging in an obliquely upward direction, is so guided that it cannot pass out of the threadbrake at the top. In order to prevent such escape at the top in all circumstances, the thread-brake in these known shuttles extends right up to the closed edge portion 14.

According to the present invention, the shape of the body of the shuttle 11 is such that it undergoes automatic cleaning.

One embodiment of such a shape is constituted by shuttle 11, which has, along the edge 14 (by which the shuttle 11 is pushed when being slipped over the coil-forming member 44) an interior unoccupied zone 34. This zone is open at the rear end of the shuttle. Provision of this zone results in the shuttle being kept very clean. The greater part of the finer particles of loose fibers collect at the thread-brake 26, 27. These particles are pushed upwards by the member 44 into the unoccupied space 34 when the member 44 passes between the portions 26 and 27, i.e., when the shuttle 11 is pushed over member 44. Here it should be noted that the upper edge of the member 44 moves into the interior of the free space, when the shuttle 11 is pushed over the member 44. (See the position 44 of the coilforming member in FIG. 1.) Since as a result of the size of this space, the fibers do not come into contact with the interior surfaces of its walls, fibers do not cling to the walls but to the coil-forming member 44. The fibers or other such contaminants do not therefore remain in the unoccupied space 34 and cannot find their way into the woven fabric. Thus the fibers and the like do not collect in the interior of the shuttle 11. It

will be understood that it is of particular importance that dirt and fibers do not build up above the thread-brake 26, 27. The presence of such an accumulation would in time prevent closing of the brake 26, 27, so that the weft threads would be inserted without being braked and a defect would occur in the fabric that could not be repaired. The fibers which adhere between the inserts 20, 22 and 21, 23 are also of course pushed upwards into the unoccupied zone 34 onto the member 44. it is possible that the emerging weft threads also contribute towards the automatic cleaning. If this is the case, the fibers are cleared out individually and not as clusters. Such a mode of operation causes no harm since it does not adversely affect the quality of the weave. In any case, experience has shown that, with the described embodiments, appreciable accumulation of fibrous material in the shuttles is prevented and that blockage of the thread-brake no longer occurs.

In order to provide this unoccupied space or zone, the upper end of the threadbrake is held at a predetermined distance from the closed edge portion 14 corresponding approximately to the height of the unoccupied space. Provision has therefore to be made for preventing the weft thread, emerging from the thread-brake 26, 27 from moving out upwards from the brake 26, 27. It is thus possible to provide an appropriate thread guide on the left or the right side of the brake 26, 27 A suitable thread guide must give free passage to the member 44 entering from the bottom when the coil of thread 43 is being passed to the shuttle 11, and must also in all cases seize and retain the weft thread as it enters from below, i.e., it must pass the thread into a guide such as slot 41. The form of construction illustrated in the embodiment shown has proved to be very advantageous. When the shuttle 11 is pushed over the member 44, the weft thread runs below the projection 39 out of the interior of the shuttle. When the shuttle 11 moves away to the left from the member 44, the next coil 43 is simultaneously pushed to the left. As the shuttle 11 passes into the shed, the thread running out of the shuttle 1 1 is pushed upwards by the reeds or reed dents. In the meantime, however, the projections 39 and 40 have again moved towards and into contact with the wall 13 of the shuttle as the result of the resilience of the arm 38, so that the thread must slip through under the projection 39 into the slot 41.

A further embodiment of a shuttle which effects a cleaning of the inner space when the shuttle 11 is pushed over the member 44 is one involving an appropriate choice of the sheet material 22 and 23. If the mutually contacting surface of the inserts 20, 22 and 21, 23 have relatively good sliding properties, the loose fibers will be pushed individually at right angles to the axis 45 of the member 44 and into the unoccupied space 34 when the shuttle 11 is slipped over the member 44, and in this space the fibers are not carried along when the shuttle 11 is moved away parallel with the axis 45, but remain on the member 44 and then fall away. As regards sliding properties, it might be mentioned that such properties virtually do not exist if bristles are present on the contact surfaces of the inserts. A material that has proved useful for the adjacent surfaces is a fabric of fibers of synthetic material, particularly nylon. With this it has been found that a not completely smooth surface, i.e., a slightly uneven surface having a woven structure, is particularly advantageous. Apart from being able to retain the individual turns in a neat manner, it also has the favorable property of enabling the weft thread to be neatly withdrawn from the shuttle 11 even if, as a result of some defect, one turn is superposed upon another. In the case of inserts made of bristles or of a fiber material it can happen that an entire turn adheres to an emerging thread and this naturally leads to defects in the weave.

Because of the continuously repeated pushing of the shuttle 11 over the coil-forming member 44, the mutually facing surfaces of the sheet material 22 and 23 undergoes slow wear. It is therefore of advantage for the sheet material 22 and 23 to be fitted in such manner that it can be easily replaced. This is so in the case of the embodiment already described, when, instead of the rivets 15, screws, which can be removed, are used.

A particularly advantageous form of such an embodiment is illustrated in FIG. 5. Because this embodiment very much resembles the embodiment shown in FIG. 2, a detailed description is not considered to be necessary. The difference between the two embodiments consists only in the manner of securing the sheets of material to the resilient material of the inserts. Referring to FIG. 5, the sheet material 52 and 53 does not completely enclose the rear side of the resilient material and 21. It covers the resilient material on the mutually facing sides thereof and is laid along the long sides of the resilient materials 20 and 21 and of the plates 24 and 25. The strips 46-49, disposed between the plates 24, and the insides, i.e., the interior surfaces, of the walls 12, 13, consist of metal strips bonded, e.g., by adhesive, on to the sheet material 52 and 53. The strips can be rendered hard, i.e., reinforced, in any other manner.

For the purpose of replacing the pieces of sheet material 52 and 53, the retaining portions or projections 18 and 19 are pressed inwards to overcome the outwardly directed bias, and the inserts 20, 22 and 21, 23, together with the plates 24, 25 and 36, are then pushed out laterally from the shuttle 11 in a manner similar to that of the previously described embodiment. The sheet material 52 and 53 is then replaced by fresh or new material, the edge strips 46, 48 and 47, 49 each being laid around the resilient substance 20 and around the plates 24 and 36. The inserts 20, 52 and 21, 53 so formed, together with the elements 24 25 and 36, are then fitted in the shuttle 11. It will be appreciated that a suction or blowing device can be provided beside the member 44 so as to remove the fibers and the like cleared from the shuttles 11.

If it is required to reinforce the cleaning of the unoccupied space 34 by means of a blowing or suction action, the space 34 should be open at both ends, so that it forms a passage. In such an arrangement, air would be blown into the passage 31 at the point 50, for example, when no coil of thread 43 is contained in the shuttle 11.

It will be appreciated that the resilient material and the sheet material used to form the inserts for holding a coil of thread within the shuttle may be made of various suitable materials; e.g., the resilient material may be foam rubber, sponge cellulose, foam polyurethane and the like and the sheet material may be a synthetic fabric made of nylon, a polyester, such as polyethylene terephthalate, polyacrylonitile, polyethylene or the like, or a film of such polymers embossed or otherwise provided with an uneven sur face.

What is claimed is:

1. A shuttle adapted to receive a coil of weft thread of predetermined length from a coil-forming member, for inserting the weft thread into a shed of a loom, said shuttle comprising a body of conchoidal shape; said body having two sidewalls that are interconnected over a portion of their peripheries to form an interconnected edge portion of the shuttle, the sidewalls being unconnected over the remaining portion of their peripheries to provide an open edge portion in said shuttle communicating with the interior of said shuttle body; retaining means in the interior of said body for receiving the coil from the coil-forming member and retaining said coil between the sidewalls when the shuttle is moved away from the coil-forming member in a direction parallel with the axis of said member; said body defining a path for the removal of particles from said weft thread during passage therethrough, comprising an unoccupied zone along the interconnected edge portion of the shuttle; said unoccupied zone being open at the rear relative to the direction in which the shuttle is moved away from the coil-forming member; said retaining means including two inserts positioned opposite each other and adjacent to the sidewalls within the interior of the body and adjoining the unoccupied zone; and there being provided a thread-brake, which comprises two end portions of a pair of plates that are biased toward each other and which also adjoin the unoccupied zone, with said inserts and said end portions positioned to allow the coil-forming member to pass therebetween and into the unoccupied zone when the shuttle is pushed over the coil-forming member.

2. The shuttle of claim 1 in which the unoccupied zone is also open at a second point forward of said rear opening towards the foremost point in relation to the direction in which the shuttle moves away from the coil-forming member, said unoccupied space being formed as a passage between the two openings so that a stream of air can flow through the passage.

3. The shuttle of claim 1 in which the two end portions forming the thread-brake are each connected to its associated plate by a supporting arm, each of the plates is held on one of the sidewalls of the shuttle, and the supporting arms are resiliently biased towards each other.

4. The shuttle of claim 1 in which there is provided a thread guide which prevents the thread from sliding out of the threadbrake and into the unoccupied zone.

5. The shuttle of claim 4 in which the thread guide comprises a slot, which is open in the direction away from the unoccupied zone and is formed by two projections, which extend from one sidewall of the shuttle beyond the rear end of the thread-brake towards the other sidewall of the shuttle.

6. The shuttle of claim 5 on which the thread guide is carried by a plate, which is held by one of the sidewalls of the shuttle.

7. The shuttle of claim 6 in which the projections are connected to the plate by a resiliently biased supporting arm, and the supporting arm is divided by a notch in the plate to form a rear zone extending in the direction in which the element is pushed over the coil-forming member.

8. The shuttle of claim 1 in which each of the inserts comprises a layer of resilient material and the layers are each covered by a flexible sheet material at least on the mutually facing sides of the inserts between which the coil-forming member is pushed when the shuttle is slipped over said member, said sheet material having a sliding surface.

9. The shuttle of claim 8 in which the surface of the sheet material is slightly uneven.

10. The shuttle of claim 9 in which the sheet material is a fabric woven from synthetic fibers.

11. The shuttle of claim 8 further comprising means for securing said sheet material to said resilient material so that said sheet material can be replaced.

12. The shuttle of claim 8 in which the resilient material for each insert is wrapped in the sheet material and the sheet material is held in position by the sidewalls of the shuttle.

13. The shuttle of claim 8 in which said retaining means includes two plates arranged in the interior of each insert between the resilient material and the sheet material wrapped around this resilient material and at the middle of the side of the resilient material adjacent to a sidewall, the plates and the sheet material are each connected to retaining projections and the retaining projections are each held by one of the sidewalls.

14. The shuttle of claim 8 in which said retaining means includes two plates each arranged between a layer of resilient material and one of the sidewalls, the sheet material is wrapped around the long edges of each of the plates, and the wrapped-around portions each form a strip and lie against the outer faces of the plates, and these strips are made of relatively rigid material. 

1. A shuttle adapted to receive a coil of weft thread of predetermined length from a coil-forming member, for inserting the weft thread into a shed of a loom, said shuttle comprising a body of conchoidal shape; said body having two sidewalls that are interconnected over a portion of their peripheries to form an interconnected edge portion of the shuttle, the sidewalls being unconnected over the remaining portion of their peripheries to provide an open edge portion in said shuttle communicating with the interior of said shuttle body; retaining means in the interior of said body for receiving the coil from the coilforming member and retaining said coil between the sidewalls when the shuttle is moved away from the coil-forming member in a direction parallel with the axis of said member; said body defining a path for the removal of particles from said weft thread during passage therethrough, comprising an unoccupied zone along the interconnected edge portion of the shuttle; said unoccupied zone being open at the rear relative to the direction in which the shuttle is moved away from the coil-forming member; said retaining means including two inserts positioned opposite each other and adjacent to the sidewalls within the interior of the body and adjoining the unoccupied zone; and there being provided a thread-brake, which comprises two end portions of a pair of plates that are biased toward each other and which also adjoin the unoccupied zone, with said inserts and said end portions positioned to allow the coil-forming member to pass therebetween and into the unoccupied zone when the shuttle is pushed over the coil-forming member.
 2. The shuttle of claim 1 in which the unoccupied zone is also open at a second point forward of said rear opening towards the foremost point in relation to the direction in which the shuttle moves away from the coil-forming member, said unoccupied space being formed as a passage between the two openings so that a stream of air can flow through the passage.
 3. The shuttle of claim 1 in which the two end portions forming the thread-brake are each connected to its associated plate by a supporting arm, each of the plates is held on one of the sidewalls of the shuttle, and the supporting arms are resiliently biased towards each other.
 4. The shuttle of claim 1 in which there is provided a thread guide which prevents the thread from sliding out of the thread-brake and into the unoccupied zone.
 5. The shuttle of claim 4 in which the thread guide comprises a slOt, which is open in the direction away from the unoccupied zone and is formed by two projections, which extend from one sidewall of the shuttle beyond the rear end of the thread-brake towards the other sidewall of the shuttle.
 6. The shuttle of claim 5 on which the thread guide is carried by a plate, which is held by one of the sidewalls of the shuttle.
 7. The shuttle of claim 6 in which the projections are connected to the plate by a resiliently biased supporting arm, and the supporting arm is divided by a notch in the plate to form a rear zone extending in the direction in which the element is pushed over the coil-forming member.
 8. The shuttle of claim 1 in which each of the inserts comprises a layer of resilient material and the layers are each covered by a flexible sheet material at least on the mutually facing sides of the inserts between which the coil-forming member is pushed when the shuttle is slipped over said member, said sheet material having a sliding surface.
 9. The shuttle of claim 8 in which the surface of the sheet material is slightly uneven.
 10. The shuttle of claim 9 in which the sheet material is a fabric woven from synthetic fibers.
 11. The shuttle of claim 8 further comprising means for securing said sheet material to said resilient material so that said sheet material can be replaced.
 12. The shuttle of claim 8 in which the resilient material for each insert is wrapped in the sheet material and the sheet material is held in position by the sidewalls of the shuttle.
 13. The shuttle of claim 8 in which said retaining means includes two plates arranged in the interior of each insert between the resilient material and the sheet material wrapped around this resilient material and at the middle of the side of the resilient material adjacent to a sidewall, the plates and the sheet material are each connected to retaining projections and the retaining projections are each held by one of the sidewalls.
 14. The shuttle of claim 8 in which said retaining means includes two plates each arranged between a layer of resilient material and one of the sidewalls, the sheet material is wrapped around the long edges of each of the plates, and the wrapped-around portions each form a strip and lie against the outer faces of the plates, and these strips are made of relatively rigid material. 